This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We aim to determine the structure of a Corynebacterium diphtheriae pilin protein. The structure will provide important information on its assembly and the mechanism of internal isopeptide bond formation. We have so far grown several crystals of this protein, both native and selenomethionine-substituted (SeMet). They typically diffract to about 2.5 [unreadable] and occasionally to 2 [unreadable] . However, the poor spot qualities and the large unit cell (~33 x 59 x 437 [unreadable] ) of these crystals severely hampered our attempts to get reliable data even at a microfocus beam line. In collaboration with Prof. Sol M. Gruner and Dr. Chae Un Kim at Cornell, we would like see if the spot qualities of these crystals improve upon high-pressure crycooling. If successful, we would like to collect full datasets of both native and SeMet crystals.